Me and my mates were thinking EXACTLY this when we were watching SW4 the other night. Also when the Millenium Falcon was tractored onto the Death Star, why didn't they just scan it for life signs? Exactly like they did with this escape pod?
Also, needs moar Lando.

It's amazing to think how the history of Star Wars would change without R2-D2. I mean, in Episode 1 (I hate the prequels but for canon's sake) if R2-D2 got shot while repairing the queen's ship and the ship got destroyed...imagine...no Darth Vader...

Imagine if Obi-Wan and Qui-Gon didn't run into Jar Jar, who helped them flee from the Trade Federation's forces on Naboo. They wouldn't have survived to find Anakin who later would become Darth Vader... thank god for Jar Jar Binks.

The reason they DIDN'T shoot down the escape pod in the actual movie is because they didn't detect any signs of life inside. They thought it was an empty pod.
Come to think of it: R2-D2 was carrying the Death Star plans at the time! If something like that happened, the Alliance AND the Empire would both be screwed!